Rail transport is a means of conveyance of passengers and goods, by way of wheeled vehicles running on rails. It is also commonly referred to as train transport. In contrast to road transport, where vehicles merely run on a prepared surface, rail vehicles are also directionally guided by the tracks on which they run. Track usually consists of steel rails installed on ties (sleepers) and ballast, on which the rolling stock, usually fitted with metal wheels, moves. However, other variations are also possible, such as slab track where the rails are fastened to a concrete foundation resting on a prepared subsurface.

Rolling stock in railway transport systems generally has lower frictional resistance when compared with highway vehicles and the passenger and freight cars (carriages and wagons) can be coupled into longer trains. The operation is carried out by a railway company, providing transport between train stations or freight customer facilities. Power is provided by locomotives which either draw electrical power from a railway electrification system or produce their own power, usually by diesel engines. Most tracks are accompanied by a signalling system. Railways are a safe land transport system when compared to other forms of transport.[Nb 1] Railway transport is capable of high levels of passenger and cargo utilization and energy efficiency, but is often less flexible and more capital-intensive than highway transport is, when lower traffic levels are considered.

The oldest, man-hauled railways date back to the 6th century B.C, with Periander, one of the Seven Sages of Greece, credited with its invention. Rail transport blossomed after the British development of the steam locomotive as a viable source of the power in the 18th and 19th centuries. With steam engines, it was possible to construct mainline railways, which were a key component of the industrial revolution. Also, railways reduced the costs of shipping, and allowed for fewer lost goods, compared with shipping, which faced occasional sinking of ships. The change from canals to railways allowed for "national markets" in which prices varied very little from city to city. Studies have shown that the invention and development of the railway in Europe was one of the most important technological inventions of the late 19th century for the United States, without which, GDP would have been lower by 7.0% in 1890.

In the 1880s, electrified trains were introduced, and also the first tramways and rapid transit systems came into being. Starting during the 1940s, the non-electrified railways in most countries had their steam locomotives replaced by diesel-electric locomotives, with the process being almost complete by 2000. During the 1960s, electrified high-speed railway systems were introduced in Japan and a few other countries. Other forms of guided ground transport outside the traditional railway definitions, such as monorail or maglev, have been tried but have seen limited use.

Pre-steam[edit]

The earliest evidence of a railway was a 6-kilometre (3.7 mi) Diolkoswagonway, which transported boats across the Corinth isthmus in Greece during the 6th century BC. Trucks pushed by slaves ran in grooves in limestone, which provided the track element. The Diolkos operated for over 600 years.[1]

The first iron plate railway, made with wrought iron plates on top of wooden rails, came into use in 1768.[8] This allowed a variation of gauge to be used. At first only balloon loops could be used for turning, but later, movable points were taken into use that allowed for switching.[9] From the 1790s, iron edge rails began to appear in Great Britain.[10] In 1803, William Jessop opened the Surrey Iron Railway in south London, arguably the world's first horse-drawn public railway.[11] The invention of the wrought iron rail by John Birkinshaw in 1820 allowed the short, brittle, and often uneven, cast iron rails to be extended to 15 feet (4.6 m) lengths.[12] These were succeeded by steel in 1857.[10]

In 1830, the first intercity route, the Liverpool and Manchester Railway, was opened. The gauge was that used for the early wagon-ways, which had been adopted for the Stockton and Darlington Railway,[20] with a 1,435 mm (4 ft 81⁄2 in) width which became known as the international standard gauge, still used by about 60% of the world's railways. This spurred the spread of rail transport outside the British Isles.

By the early 1850s, Great Britain had over 7,000 miles (11,000 km) of railway, a stunning achievement given that only twenty years had elapsed since the opening of the Liverpool and Manchester Railway.[21]

Early railroads in the US[edit]

Railroads (as they are known in the US) were built on a far larger scale than those in Continental Europe, both in terms of the distances covered and also in the loading gauge adopted, which allowed for heavier locomotives and double-deck trains. The railroad era in the United States began in 1830 when Peter Cooper's locomotive, Tom Thumb, first steamed along 13 miles (21 km) of Baltimore and Ohio railroad track.[22] In 1833, the nation's second railroad ran 136 miles (219 km) from Charleston to Hamburg in South Carolina.[23] Not until the 1850s, though, did railroads offer long distance service at reasonable rates. A journey from Philadelphia to Charleston involved eight different gauges, which meant that passengers and freight had to change trains seven times. Only at places like Bowling Green, Kentucky, were the railroads connected to one another.

The Baltimore and Ohio Railroad that opened in 1830 was the first to evolve from a single line to a network in the United States.[24] By 1831, a steam railway connected Albany and Schenectady, New York, a distance of 16 miles (26 km), which was covered in 40 minutes.[25]

The years between 1850 and 1890 saw phenomenal growth in the US railroad system, which at its peak constituted one third of the world's total mileage.[26][not in citation given] Although the American Civil War placed a temporary halt to major new developments, the conflict did demonstrate the enormous strategic importance of railways at times of war. After the war, major developments include the first elevated railway built in New York in 1867 as well as the symbolically important first transcontinental railroad completed in 1869.[27]

Electrification and dieselisation[edit]

Experiments with electrical railways were started by Robert Davidson in 1838. He completed a battery-powered carriage capable of 6.4 km/h (4 mph). The Gross-Lichterfelde Tramway was the first to use electricity fed to the trains en route, when it opened in 1881. Overhead wires were taken into use in the Mödling and Hinterbrühl Tram in Austria in October 1883. At first, this was taken into use on tramways that, until then, had been horse-drawn tramcars. The first conventional completely electrified railway mainline was the 106 km Valtellina line in Italy that was opened on 4 September 1902.

Steam locomotives require large pools of labour to clean, load, maintain and run. After World War II, dramatically increased labour costs in developed countries made steam an increasingly costly form of motive power. At the same time, the war had forced improvements in internal combustion engine technology that made diesel locomotives cheaper and more powerful. This caused many railway companies to initiate programmes to convert all unelectrified sections from steam to diesel locomotion.

Following the large-scale construction of motorways after the war, rail transport became less popular for commuting and air transport started taking large market shares from long-haul passenger trains. Most tramways were either replaced by rapid transit or buses, while high transshipment costs caused short-haul freight trains to become uncompetitive. The 1973 oil crisis led to a change of mind set and most tram systems that had survived into the 1970s remain today. At the same time, containerization allowed freight trains to become more competitive and participate in intermodal freight transport. With the 1964 introduction of the Shinkansenhigh-speed rail in Japan, trains could again have a dominant position on intercity travel. During the 1970s, the introduction of automated rapid transit systems allowed cheaper operation. The 1990s saw an increased focus on accessibility and low-floor trains. Many tramways have been upgraded to light rail and many cities that closed their old tramways have reopened new light railway systems.

Innovations[edit]

Many benchmarks in equipment and infrastructure led to the growing use of railways. Some innovative features taking place in the 19th and 20th centuries included wood cars replaced with all-steel cars, which provided better safety and maintenance; iron rails replaced with steel rails, which provided higher speed and capacity with lower weight and cost; stove-heated cars to steam-heating cars, piped from locomotive; gas lighting to electric lighting, with use of battery/alternator unit beneath the car; development of air-conditioning with additional underbody equipment and ice compartment. Some innovative rolling stock included the lightweight, diesel-powered streamliner, which was a modernistic, aerodynamically styled train with flowing contours; then came the ultra-lightweight car with internal combustion engine in each train's power car; others included the dome car, turbined-powered trains, bi-level rolling stock, and the high-tech/high-speed electric trains.[29]

Even more, in the first half of the 20th century, infrastructure elements adopted technological changes including the continuously welded rail that was 1⁄4 mile (0.40 km) long; concrete tie usage; double tracking major lines; intermodal terminal and handling technology; advances in diesel-electric propulsion to include AC traction systems and propulsion braking systems; and just-in-time inventory control. Beyond technology, even management of systems saw improvements with the adoption of environmental impact concerns; heightened concern of employee and public safety; introduction of urban area rail networks and public agencies to manage them; and downsizing of industry employment with greater use of contractors and consultants.[30]

Trains[edit]

A train is a connected series of rail vehicles that move along the track. Propulsion for the train is provided by a separate locomotive or from individual motors in self-propelled multiple units. Most trains carry a revenue load, although non-revenue cars exist for the railway's own use, such as for maintenance-of-way purposes. The engine driver (engineer in North America) controls the locomotive or other power cars, although people movers and some rapid transits are under automatic control.

Haulage[edit]

Russian 2TE10U Diesel-electric locomotive

Traditionally, trains are pulled using a locomotive. This involves one or more powered vehicles being located at the front of the train, providing sufficient tractive force to haul the weight of the full train. This arrangement remains dominant for freight trains and is often used for passenger trains. A push-pull train has the end passenger car equipped with a driver's cab so the engine driver can remotely control the locomotive. This allows one of the locomotive-hauled train's drawbacks to be removed, since the locomotive need not be moved to the front of the train each time the train changes direction. A railroad car is a vehicle used for the haulage of either passengers or freight.

A multiple unit has powered wheels throughout the whole train. These are used for rapid transit and tram systems, as well as many both short- and long-haul passenger trains. A railcar is a single, self-powered car, and may be electrically-propelled or powered by a diesel engine. Multiple units have a driver's cab at each end of the unit and were developed following the ability to build electric motors and engines small enough to fit under the coach. There are only a few freight multiple units, most of which are high-speed post trains.

Electric locomotives draw power from a stationary source via an overhead wire or third rail. Some also or instead use a battery. In locomotives that are powered by high voltage alternating current, a transformer in the locomotive converts the high voltage, low current power to low voltage, high current used in the traction motors that power the wheels. Modern locomotives may use three-phase AC induction motors or direct current motors. Under certain conditions, electric locomotives are the most powerful traction.[citation needed] They are also the cheapest to run and provide less noise and no local air pollution.[citation needed] However, they require high capital investments both for the overhead lines and the supporting infrastructure, as well as the generating station that is needed to produce electricity. Accordingly, electric traction is used on urban systems, lines with high traffic and for high-speed rail.

Passenger trains[edit]

A passenger train travels between stations where passengers may embark and disembark. The oversight of the train is the duty of a guard/train manager/conductor. Passenger trains are part of public transport and often make up the stem of the service, with buses feeding to stations. Passenger trains provide long-distance intercity travel, daily commuter trips, or local urban transit services. They even include a diversity of vehicles, operating speeds, right-of-way requirements, and service frequency. Passenger trains usually can be divided into two operations: intercity railway and intracity transit. Whereas as intercity railway involve higher speeds, longer routes, and lower frequency (usually scheduled), intracity transit involves lower speeds, shorter routes, and higher frequency (especially during peak hours).[30]

High-speed rail are special inter-city trains that operate at much higher speeds than conventional railways, the limit being regarded at 200 to 320 kilometres per hour (120 to 200 mph). High-speed trains are used mostly for long-haul service and most systems are in Western Europe and East Asia. The speed record is 574.8 km/h (357.2 mph), set by a modified French TGV.[31][32]Magnetic levitation trains such as the Shanghai airport train use under-riding magnets which attract themselves upward towards the underside of a guideway and this line has achieved somewhat higher peak speeds in day-to-day operation than conventional high-speed railways, although only over short distances. Due to their heightened speeds, route alignments for high-speed rail tend to have shallower grades and broader curves than conventional railways.

Their high kinetic energy translates to higher horsepower-to-ton ratios (e.g. 20 horsepower per short ton or 16 kilowatts per tonne); this allows trains to accelerate and maintain higher speeds and negotiate steep grades as momentum builds up and recovered in downgrades (reducing cut, fill, and tunneling requirements). Since lateral forces act on curves, curvatures are designed with the highest possible radius. All these features are dramatically different from freight operations, thus justifying exclusive high-speed rail lines if it is economically feasible.[30]

Rail network in Paris, France

Higher-speed rail services are intercity rail services that have top speeds higher than conventional intercity trains but the speeds are not as high as those in the high-speed rail services. These services are provided after improvements to the conventional rail infrastructure in order to support trains that can operate safely at higher speeds.

High speed railway (High Speed Railroad/Railway & Railroad/Railway high speed) commonly referred to as the High-speed Rail (abbre:HR[hairei]), is a kind of operating speed of at least eighty percent more than in the whole operation process of distance over 200 km/h (>200 km/h&130MPH) railway. As of 2014, the operating speed of High-speed Rail systems in the world are running about all set at 300 kilometers per hour, a few systems have relatively high speed. For High-speed Rail speed can be considered: 1 is High-speed Rail lines after transformation from common railroad, such High-speed Rail maximum speed of approximately 250 km/h (250 km/h&150MPH). 2 is the construction standards for the ballasted bed (stone ballast) high-speed railway was built, such High-speed Rail maximum speed of approximately 320 km / h (320 km/h&200MPH). 3 is the construction of ballastless track technology standards (that is popular opinion of to lay the rail on the reinforced concrete pavement directly ) was built, to China High-speed Rail represented such High-speed Rail mostly built in high-speed bridge (overhead bridge), so called air railway (air railroad), such High-speed Rail maximum speed of approximately 400 km/h (400 km/h&250MPH). (the above rate refers to the commercial operation speed)

High speed railway is a high-tech integrated system, including 6 aspects: infrastructure, 1 parts, also including the station construction. The 2 part: high speed train. The 3 part: electricity and telecommunications, including electrical and contact network, safe and reliable communication, signal, dispatching center console. 4: safety control part, including meteorological conditions monitoring, line monitoring, automatic train control and retrieval, road, vehicle automatic monitoring and response system. 5: maintenance and maintenance section, including the line maintenance, high speed train (highspeed divided dynamic train abbre:HDDT) maintenance and repair, involving a variety of instrumentation maintenance and repair, and maintenance of equipment and monitoring instruments. 6: the other parts, including passenger safety assessment sent, High-speed Rail prospective study, the new High-speed Rail line and the new high speed train or high speed train test, High-speed Rail financial, High-speed Rail operational data storage and analysis and etc..

Rapid transit is an intracity system built in large cities and has the highest capacity of any passenger transport system. It is usually grade-separated and commonly built underground or elevated. At street level, smaller trams can be used. Light rails are upgraded trams that have step-free access, their own right-of-way and sometimes sections underground. Monorail systems are elevated, medium-capacity systems. A people mover is a driverless, grade-separated train that serves only a few stations, as a shuttle. Due to the lack of uniformity of rapid transit systems, route alignment varies, with diverse rights-of-way (private land, side of road, street median) and geometric characteristics (sharp or broad curves, steep or gentle grades). For instance, the Chicago 'L' trains are designed with extremely short cars to negotiate the sharp curves in the Loop. New Jersey's PATH has similar-sized cars to accommodate curves in the trans-Hudson tunnels. San Francisco's BART operates large cars on its well-engineered routes.[30]

Freight train[edit]

A freight train hauls cargo using freight cars specialized for the type of goods. Freight trains are very efficient, with economy of scale and high energy efficiency. However, their use can be reduced by lack of flexibility, if there is need of transshipment at both ends of the trip due to lack of tracks to the points of pick-up and delivery. Authorities often encourage the use of cargo rail transport due to its environmental profile.[33]

Right of way[edit]

Railway tracks are laid upon land owned or leased by the railway company. Owing to the desirability of maintaining modest grades, rails will often be laid in circuitous routes in hilly or mountainous terrain. Route length and grade requirements can be reduced by the use of alternating cuttings, bridges and tunnels—all of which can greatly increase the capital expenditures required to develop a right of way, while significantly reducing operating costs and allowing higher speeds on longer radius curves. In densely urbanized areas, railways are sometimes laid in tunnels to minimize the effects on existing properties.

Track consists of two parallel steel rails, anchored perpendicular to members called ties (sleepers) of timber, concrete, steel, or plastic to maintain a consistent distance apart, or rail gauge. Rail gauges are usually categorised as Standard gauge (1,435 mm (4 ft 81⁄2 in)) used on approximately 60% of the world's existing railway lines, Broad gauge and Narrow gauge. In addition to the rail gauge, the tracks will be laid to conform with a Loading gauge which defines the maximum height and width for railway vehicles and their loads to ensure safe passage through bridges, tunnels and other structures.

The track guides the conical, flanged wheels, keeping the cars on the track without active steering and therefore allowing trains to be much longer than road vehicles. The rails and ties are usually placed on a foundation made of compressed earth on top of which is placed a bed of ballast to distribute the load from the ties and to prevent the track from buckling as the ground settles over time under the weight of the vehicles passing above.

The ballast also serves as a means of drainage. Some more modern track in special areas is attached by direct fixation without ballast. Track may be prefabricated or assembled in place. By welding rails together to form lengths of continuous welded rail, additional wear and tear on rolling stock caused by the small surface gap at the joints between rails can be counteracted; this also makes for a quieter ride (passenger trains).

On curves the outer rail may be at a higher level than the inner rail. This is called superelevation or cant. This reduces the forces tending to displace the track and makes for a more comfortable ride for standing livestock and standing or seated passengers. A given amount of superelevation will be the most effective over a limited range of speeds.

Turnouts, also known as points and switches, are the means of directing a train onto a diverging section of track. Laid similar to normal track, a point typically consists of a frog (common crossing), check rails and two switch rails. The switch rails may be moved left or right, under the control of the signalling system, to determine which path the train will follow.

Spikes in wooden ties can loosen over time, but split and rotten ties may be individually replaced with new wooden ties or concrete substitutes. Concrete ties can also develop cracks or splits, and can also be replaced individually. Should the rails settle due to soil subsidence, they can be lifted by specialized machinery and additional ballast tamped under the ties to level the rails.

Periodically, ballast must be removed and replaced with clean ballast to ensure adequate drainage. Culverts and other passages for water must be kept clear lest water is impounded by the trackbed, causing landslips. Where trackbeds are placed along rivers, additional protection is usually placed to prevent streambank erosion during times of high water. Bridges require inspection and maintenance, since they are subject to large surges of stress in a short period of time when a heavy train crosses.

Train inspection systems[edit]

The inspection of railway equipment is essential for the safe movement of trains. Many types of defect detectors are in use on the world's railroads. These devices utilize technologies that vary from a simplistic paddle and switch to infrared and laser scanning, and even ultrasonic audio analysis. Their use has avoided many rail accidents over the 70 years they have been used.

Signalling[edit]

Bardon Hill box in England is a Midland Railway box dating from 1899, although the original mechanical lever frame has been replaced by electrical switches. Seen here in 2009.

Railway signalling is a system used to control railway traffic safely to prevent trains from colliding. Being guided by fixed rails with low friction, trains are uniquely susceptible to collision since they frequently operate at speeds that do not enable them to stop quickly or within the driver's sighting distance. Most forms of train control involve movement authority being passed from those responsible for each section of a rail network to the train crew. Not all methods require the use of signals, and some systems are specific to single track railways.

The signalling process is traditionally carried out in a signal box, a small building that houses the lever frame required for the signalman to operate switches and signal equipment. These are placed at various intervals along the route of a railway, controlling specified sections of track. More recent technological developments have made such operational doctrine superfluous, with the centralization of signalling operations to regional control rooms. This has been facilitated by the increased use of computers, allowing vast sections of track to be monitored from a single location. The common method of block signalling divides the track into zones guarded by combinations of block signals, operating rules, and automatic-control devices so that only one train may be in a block at any time.

Electrification[edit]

The electrification system provides electrical energy to the trains, so they can operate without a prime mover on board. This allows lower operating costs, but requires large capital investments along the lines. Mainline and tram systems normally have overhead wires, which hang from poles along the line. Grade-separated rapid transit sometimes use a ground third rail.

Power may be fed as direct or alternating current. The most common DC voltages are 600 and 750 V for tram and rapid transit systems, and 1,500 and 3,000 V for mainlines. The two dominant AC systems are 15 kV AC and 25 kV AC.

Stations[edit]

A railway station serves as an area where passengers can board and alight from trains. A goods station is a yard which is exclusively used for loading and unloading cargo. Large passenger stations have at least one building providing conveniences for passengers, such as purchasing tickets and food. Smaller stations typically only consist of a platform. Early stations were sometimes built with both passenger and goods facilities.[34]

Platforms are used to allow easy access to the trains, and are connected to each other via underpasses, footbridges and level crossings. Some large stations are built as culs-de-sac, with trains only operating out from one direction. Smaller stations normally serve local residential areas, and may have connection to feeder bus services. Large stations, in particular central stations, serve as the main public transport hub for the city, and have transfer available between rail services, and to rapid transit, tram or bus services.

Operations[edit]

Ownership[edit]

In the United States, railroads such as the Union Pacific traditionally own and operate both their rolling stock and infrastructure, with the company itself typically being privately owned.

Since the 1980s, there has been an increasing trend to split up railway companies, with companies owning the rolling stock separated from those owning the infrastructure. This is particularly true in Europe, where this arrangement is required by the European Union. This has allowed open access by any train operator to any portion of the European railway network. This is different in the UK however, where the railway track is state owned, with a public controlled body (Network Rail) running, maintaining and developing the track.[35]

In the U.S., virtually all rail networks and infrastructure outside the Northeast Corridor are privately owned by freight lines. Passenger lines, primarily Amtrak, operate as tenants on the freight lines. Consequently, operations must be closely synchronized and coordinated between freight and passenger railroads, with passenger trains often being dispatched by the host freight railroad. Due to this shared system, both are regulated by the Federal Railroad Administration (FRA) and may follow the AREMA recommended practices for track work and AAR standards for vehicles.[30]

Financing[edit]

The main source of income for railway companies is from ticket revenue (for passenger transport) and shipment fees for cargo. Discounts and monthly passes are sometimes available for frequent travellers (e.g. season ticket and rail pass). Freight revenue may be sold per container slot or for a whole train. Sometimes, the shipper owns the cars and only rents the haulage. For passenger transport, advertisement income can be significant.

Governments may choose to give subsidies to rail operation, since rail transport has fewer externalities than other dominant modes of transport. If the railway company is state-owned, the state may simply provide direct subsidies in exchange for increased production. If operations have been privatized, several options are available. Some countries have a system where the infrastructure is owned by a government agency or company—with open access to the tracks for any company that meets safety requirements. In such cases, the state may choose to provide the tracks free of charge, or for a fee that does not cover all costs. This is seen as analogous to the government providing free access to roads. For passenger operations, a direct subsidy may be paid to a public-owned operator, or public service obligation tender may be helt, and a time-limited contract awarded to the lowest bidder.

Amtrak, the US passenger rail service, and Canada's Via Rail are private railroad companies chartered by their respective national governments. As private passenger services declined because of competition from automobiles and airlines, they became shareholders of Amtrak either with a cash entrance fee or relinquishing their locomotives and rolling stock. The government subsidizes Amtrak by supplying start-up capital and making up for losses at the end of the fiscal year.[29]

Safety[edit]

According to Eurostat and European Railway Agency, in European railway mode of transport, there is a fatality risk for passengers and occupants 28 times lower compared with car usage. Based on data by EU-27 member nations, 2008-2010.[36][37]

Trains can travel at very high speed, but they are heavy, are unable to deviate from the track and require a great distance to stop. Possible accidents include derailment (jumping the track), a collision with another train or collision with automobiles, other vehicles or pedestrians at level crossings. The last accounts for the majority of rail accidents and casualties. The most important safety measures to prevent accidents are strict operating rules, e.g. railway signalling and gates or grade separation at crossings. Train whistles, bells or horns warn of the presence of a train, while trackside signals maintain the distances between trains.

An important element in the safety of many high-speed inter-city networks such as Japan's Shinkansen is the fact that trains only run on dedicated railway lines, without level crossings. This effectively eliminates the potential for collision with automobiles, other vehicles or pedestrians, vastly reduces the likelihood of collision with other trains and helps ensure services remain timely.

In order to ensure the highest possible degree of safety, independent scrutiny and assessment of safety-critical products and processes is of vital importance.[38]

Maintenance[edit]

As in any infrastructure asset, railways must keep up with periodic inspection and maintenance in order to minimize effect of infrastructure failures that can disrupt freight revenue operations and passenger services. Because passengers are considered the most crucial cargo and usually operate at higher speeds, steeper grades, and higher capacity/frequency, their lines are especially important. Inspection practices include track geometry cars or walking inspection. Curve maintenance especially for transit services includes gauging, fastener tightening, and rail replacement. In order to ensure the highest possible quality and gain the specialized skills[39] and expertise for a specific project, a Railway Undertaking (RU) or subcontractor look often for professional outsourcing staff.[40]

Rail corrugation is a common issue with transit systems due to the high number of light-axle, wheel passages which result in grinding of the wheel/rail interface. Since maintenance may overlap with operations, maintenance windows (nighttime hours, off-peak hours, altering train schedules or routes) must be closely followed. In addition, passenger safety during maintenance work (inter-track fencing, proper storage of materials, track work notices, hazards of equipment near states) must be regarded at all times. At times, maintenance access problems can emerge due to tunnels, elevated structures, and congested cityscapes. Here, specialized equipment or smaller versions of conventional maintenance gear are used.[30]

Unlike highways or road networks where capacity is disaggregated into unlinked trips over individual route segments, railway capacity is fundamentally considered a network system. As a result, many components are causes and effects of system disruptions. Maintenance must acknowledge the vast array of a route's performance (type of train service, origination/destination, seasonal impacts), line's capacity (length, terrain, number of tracks, types of train control), trains throughput (max speeds, acceleration/deceleration rates), and service features with shared passenger-freight tracks (sidings, terminal capacities, switching routes, and design type).[30]

Social, Economical and Energetic aspects[edit]

Energy[edit]

Rail transport is an energy-efficient[41] but capital-intensive, means of mechanized land transport. The tracks provide smooth and hard surfaces on which the wheels of the train can roll with a minimum of friction. Moving a vehicle on and/or through a medium (land, sea, or air) requires overcoming resistance to motion. A land vehicle's total resistance (in pounds or Newtons) is a quadratic function of the vehicle's speed:

where:

R denotes total resistance

a denotes initial constant resistance

b denotes velocity-related constant

c denotes constant that is function of shape, frontal area, and sides of vehicle

Essentially, resistance differs between vehicle's contact point and surface of roadway. Metal wheels on metal rails have a significant advantage of overcoming resistance compared to rubber-tired wheels on any road surface (railway – 0.001g at 10 miles per hour (16 km/h) and 0.024g at 60 miles per hour (97 km/h); truck – 0.009g at 10 miles per hour (16 km/h) and 0.090 at 60 miles per hour (97 km/h)). In terms of cargo capacity combining speed and size being moved in a day:

long-haul train – can carry 500,000 tmi/day (730,000 tkm/day)[30] Most trains take 250–400 trucks off the road, thus making the road more safe.

In terms of the horsepower to weight ratio, a slow-moving barge requires 0.2 horsepower per short ton (0.16 kW/t), a railway and pipeline requires 2.5 horsepower per short ton (2.1 kW/t), and truck requires 10 horsepower per short ton (8.2 kW/t). However, at higher speeds, a railway overcomes the barge and proves most economical.[30]

As an example, a typical modern wagon can hold up to 113 tonnes (125 short tons) of freight on two four-wheel bogies. The track distributes the weight of the train evenly, allowing significantly greater loads per axle and wheel than in road transport, leading to less wear and tear on the permanent way. This can save energy compared with other forms of transport, such as road transport, which depends on the friction between rubber tires and the road. Trains have a small frontal area in relation to the load they are carrying, which reduces air resistance and thus energy usage.

In addition, the presence of track guiding the wheels allows for very long trains to be pulled by one or a few engines and driven by a single operator, even around curves, which allows for economies of scale in both manpower and energy use; by contrast, in road transport, more than two articulations causes fishtailing and makes the vehicle unsafe.

Energy efficiency[edit]

Considering only the energy spent to move the means of transport, and using the example of the urban area of Lisbon, trains seem to be on average 20 times more efficient than automobiles for transportation of passengers, if we consider energy spent per passenger-distance with similar occupation ratios.[42] Considering an automobile with a consumption of around 6 l/100 km (47 mpg-imp; 39 mpg-US) of gasoline, the average car in Europe has an occupancy of around 1.2 passengers per automobile (occupation ratio around 24%) and that one litre of gasoline amounts to about 8.8 kWh (32 MJ), equating to an average of 441 Wh (1,590 kJ) per passenger-km. This compares to a modern train with an average occupancy of 20% and a consumption of about 8.5 kW·h/km (31 MJ/km; 13.7 kW·h/mi), equating to 21.5 Wh (77 kJ) per passenger-km, 20 times less than the automobile.

Usage[edit]

Due to these benefits, rail transport is a major form of passenger and freight transport in many countries. It is ubiquitous in Europe, with an integrated network covering virtually the whole continent. In India, China, South Korea and Japan, many millions use trains as regular transport. In North America, freight rail transport is widespread and heavily used, but intercity passenger rail transport is relatively scarce outside the Northeast Corridor, due to increased preference of other modes, particularly automobiles and airplanes.[29][43]

Indian locomotive class WDG-3A one of the high power locomotives in India

South Africa, northern Africa and Argentina have extensive rail networks, but some railways elsewhere in Africa and South America are isolated lines. Australia has a generally sparse network befitting its population density but has some areas with significant networks, especially in the southeast. In addition to the previously existing east-west transcontinental line in Australia, a line from north to south has been constructed. The highest railway in the world is the line to Lhasa, in Tibet,[44] partly running over permafrost territory. Western Europe has the highest railway density in the world and many individual trains there operate through several countries despite technical and organizational differences in each national network.

Social and economic benefits[edit]

Railways are central to the formation of modernity and ideas of progress.[45] Railways contribute to social vibrancy and economic competitiveness by transporting multitudes of customers and workers to city centers and inner suburbs. Hong Kong has recognized rail as "the backbone of the public transit system" and as such developed their franchised bus system and road infrastructure in compherensive alignment with their rail services.[46] China's large cities such as Beijing, Shanghai, and Guangzhou recognize rail transit lines as the framework and bus lines as the main body to their metropolitan transportation systems.[47] The Japanese Shinkansen was built to meet the growing traffic demand in the "heart of Japan's industry and economy" situated on the Tokyo-Kobe line.[48]

German soldiers in a railway car on the way to the front in August 1914. The message on the car reads Von München über Metz nach Paris. (From Munich via Metz to Paris).

During much of the 20th Century, rail was an invaluable element of military mobilization, allowing for the quick and efficient transport of large numbers of reservists to their mustering-points, and infantry soldiers to the front lines. However, by the 21st Century, rail transport - limited to locations on the same continent, and vulnerable to air attack - had largely been displaced by the adoption of aerial transport.

^"Steam train anniversary begins". BBC. 21 February 2004. Retrieved 8 May 2011. A south Wales town has begun months of celebrations to mark the 200th anniversary of the invention of the steam locomotive. Merthyr Tydfil was the location where, on 21 February 1804, Richard Trevithick took the world into the railway age when he set one of his high-pressure steam engines on a local iron master's tram rails

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